The present invention concerns advanced epoxy resins and coatings containing same.
Coatings have heretofore been prepared by reacting diglycidyl ethers of dihydric phenols with dihydric phenols and subsequently curing same with a suitable curing agent or, for the very high molecular weight advanced products, merely applying a solution of such resin and evaporating the solvent therefrom. While such coatings have good physical and chemical properties, they are somewhat lacking in flexibility and flow. There are some applications such as automotive primer surfacer, automotive stone chip coatings, coil coatings and the like where somewhat reduced physical and/or chemical properties can be accepted for an improvement in flexibility or flow or a reduction in the amount of volatile solvent required to achieve the same application viscosity. Also, because the solution coatings contain solvents which must either be recovered or vented into the atmosphere, the latter of which is not environmentally acceptable, solvent recovery systems are required.
The present invention provides for coatings having improved flexibility and requiring less solvent to achieve desirable application viscosities. The present invention provides coatings having an improvement in flow characteristics and lower melt viscosities as compared to coatings prepared from an advanced epoxy resin prepared from an aromatic diepoxide and a dihydric phenol. The present invention provides coatings having an improvement in solvent resistance, water resistance (moisture sensitivity), corrosion resistance or ability to apply electrodeposition coatings at higher voltages as compared to coatings prepared from an advanced epoxy resin prepared from an aliphatic diepoxide and a dihydric phenol.